// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_CERT_X509_UTIL_H_
#define NET_CERT_X509_UTIL_H_

#include <stdint.h>

#include <memory>
#include <string>

#include "base/memory/ref_counted.h"
#include "base/time/time.h"
#include "net/base/net_export.h"

namespace crypto {
class ECPrivateKey;
class RSAPrivateKey;
}

namespace net {

class X509Certificate;

namespace x509_util {

    // Supported digest algorithms for signing certificates.
    enum DigestAlgorithm {
        DIGEST_SHA1,
        DIGEST_SHA256
    };

    // Generate a 'tls-server-end-point' channel binding based on the specified
    // certificate. Channel bindings are based on RFC 5929.
    NET_EXPORT_PRIVATE bool GetTLSServerEndPointChannelBinding(
        const X509Certificate& certificate,
        std::string* token);

    // Creates a public-private keypair and a self-signed certificate.
    // Subject, serial number and validity period are given as parameters.
    // The certificate is signed by the private key in |key|. The key length and
    // signature algorithm may be updated periodically to match best practices.
    //
    // |subject| is a distinguished name defined in RFC4514 with _only_ a CN
    // component, as in:
    //   CN=Michael Wong
    //
    // SECURITY WARNING
    //
    // Using self-signed certificates has the following security risks:
    // 1. Encryption without authentication and thus vulnerable to
    //    man-in-the-middle attacks.
    // 2. Self-signed certificates cannot be revoked.
    //
    // Use this certificate only after the above risks are acknowledged.
    NET_EXPORT bool CreateKeyAndSelfSignedCert(
        const std::string& subject,
        uint32_t serial_number,
        base::Time not_valid_before,
        base::Time not_valid_after,
        std::unique_ptr<crypto::RSAPrivateKey>* key,
        std::string* der_cert);

    // Creates a self-signed certificate from a provided key, using the specified
    // hash algorithm.  You should not re-use a key for signing data with multiple
    // signature algorithms or parameters.
    NET_EXPORT bool CreateSelfSignedCert(crypto::RSAPrivateKey* key,
        DigestAlgorithm alg,
        const std::string& subject,
        uint32_t serial_number,
        base::Time not_valid_before,
        base::Time not_valid_after,
        std::string* der_cert);

    // Comparator for use in STL algorithms that will sort client certificates by
    // order of preference.
    // Returns true if |a| is more preferable than |b|, allowing it to be used
    // with any algorithm that compares according to strict weak ordering.
    //
    // Criteria include:
    // - Prefer certificates that have a longer validity period (later
    //   expiration dates)
    // - If equal, prefer certificates that were issued more recently
    // - If equal, prefer shorter chains (if available)
    class NET_EXPORT_PRIVATE ClientCertSorter {
    public:
        ClientCertSorter();

        bool operator()(
            const scoped_refptr<X509Certificate>& a,
            const scoped_refptr<X509Certificate>& b) const;

    private:
        base::Time now_;
    };

} // namespace x509_util

} // namespace net

#endif // NET_CERT_X509_UTIL_H_
